How old do I need to be to file Form N-400

The naturalization process should be started only after you make all the necessary checks of being eligible to get US citizenship.

There are several requirements to be met for such people. One of them is age. People under 18 are not allowed to file Form N-400.

If a parent makes an application for a child who is not 18 yet to become a US citizen, it is necessary to file Application for Certificate of Citizenship (Form N-600) or Application for Citizenship and Issuance of a Certificate under Section 322 (Form N-600K).